1. Technical Field
The present invention relates to a technology of reducing defects in the display of a liquid crystal panel.
2. Related Art
A liquid crystal panel has a configuration where liquid crystal is interposed by a pair of substrates which are separated by a constant gap.
More specifically, the liquid crystal panel is configured by arraying pixel electrodes of pixels in a matrix shape on the one substrate and by disposing a common electrode on the other substrate so as to be common to the pixels, so that the liquid crystal is interposed by the pixel electrodes and the common electrode. If a voltage according to a grayscale level is applied and sustained between the pixel electrode and the common electrode, an alignment state of the liquid crystal is defined for each pixel, so that transmittance or reflectance is controlled. Therefore, in the above configuration, it may be stated that, in the electric field exerted on the liquid crystal molecule, only the component in the direction from the pixel electrode toward the common electrode (or the opposite direction), that is, the component in the vertical direction (longitudinal direction) with respect to the surface of the substrate is contributed to the display control.
However, recently, the pixel pitch is narrowed for the miniaturization and the high accuracy. Accordingly, there is an electric field generated from the adjacent pixel electrodes, that is the electric field in the direction (transverse direction) parallel to the surface of the substrate, so that the influence thereof may not be ignored. For example, if the transverse electric field is added to the liquid crystal which is to be driven by the electric field in the longitudinal direction, for example, in a VA (Vertical Alignment) scheme, a TN (Twisted Nematic) scheme, or the like, there are alignment defects (reverse tilt domain) in the liquid crystal occurs, so that there is a problem in that defects in the display occurs.
In order to reduce the influence of the reverse tilt domain, there is disclosed a technology (for example, refer to JP-A-6-34965 (FIG. 1)) of contriving a structure of the liquid crystal panel such as defining a shape of a light-shielding layer (aperture portion) in coincidence with each pixel electrode, or there is disclosed a technology (for example, refer to JP-A-2009-69608 (FIG. 2)) where, if an average luminance value calculated from video signals is equal to or lower than a threshold value, it is determined that the reverse tilt domain has occurred and video signals, of which the value is equal to or higher than a specific value, are clipped.
However, in the technology of reducing the reverse tilt domain by using the structure of the liquid crystal panel, there are problems in that the aperture ratio may be easily lowered and in that a liquid crystal panel that is already manufactured may not be employed without contrivance of the structure thereof. On the other hand, in the technology where the video signals of which the values are equal to or higher than the specific value are clipped, there is a problem in that the brightness of the displayed image is limited to the specific value.